Abstract: The development of water system pattern is the most meaningful geological event that wasaccurately and completely recorded during the process of Late Quaternary in the area with themost active tectonic movements. In this paper, we carry out a study on the longitudinal profileof the 6 rivers in the Simao Basin, located in the southwest of China, by fitting thecharacteristics of the river longitudinal profile, and analyzing the evolution process of theirlongitudinal Profile based on the stream power incision model. The result shows：1）that the low-level rivers are better in accordance with the Horton Law, and the high-level riversdeveloped along the fault zone show obvious deviation from the Horton Law; 2）that S-A fitting graphics of all rivers are arranged in concave and convex at intervals; 3）that the lithologicvariations do not correspond with changes in the characteristics of knickpoints. All the resultsinferred that Simao Basin is currently influenced by strike-slip fault.